Systems for monitoring regions of commercial and industrial establishments have been found to be useful for security and safety purposes. One type of system includes a control unit which is coupled to a plurality of spaced apart ambient condition detectors. The detectors can for example include smoke, flame, temperature or gas sensors. Such detectors are usually removably mountable on a permanently installed base. A given detector can be removed for maintenance or repair and then replaced on the respective base.
When the detector, or detectors is, are replaced on the respective base or bases, there is not necessarily any assurance that a given detector will be replaced on the base from which it was removed. This presents a problem to the control unit which must keep track of the locations of the detectors so as to be able to map a particular detector, which may be indicating the presence of an ambient condition of concern, into a physical location.
One solution to this problem has been disclosed and claimed in U.S. Pat. No. 5,357,243 entitled Electrical Unit with an Adjustable Mechanical Switch For Address Verification, assigned to the Assignee hereof. The system of the '243 patent while effective, required that address switches installed on the detector be set to an appropriate address corresponding to the address of the base. Hence, a mismatch between a base and a detector kept the detector from engaging the base.
In another known approach, the detectors are coupled in series to a communication line. The detectors open circuit the communication line, and then close circuit the line sequentially.
The control unit senses the first open circuited detector and it closes the circuit therethrough. The control unit then senses the second detector and it closes the circuit therethrough. Each of the detectors, which are serially linked to at least one other detector is then located relative to the adjacent detectors. In this approach, the control element is the only recipient of communications from the respective detectors. Detector identification takes place using current signals.
In yet another known system, the control element issues a command to a selected detector directing it to send a current pulse to the control element. The control element then checks to determine which detectors sensed the current pulse. Each detector on the loop between the current transmitting detector and the control element will sense the current pulse. This information can be used to establish the relative locations of the various detectors on the communications link.
There continues to be a need for systems and methods which can be used to automatically determine detector locations. Preferably such functionality could be provided without significantly increasing the complexity or cost of the associated monitoring systems.